DE-A1-3,331,112 discloses a device for the dissIpation of heat from printed circuit boards. Electrical components are mounted on one side of the printed circuit board. A good heat conducting layer is applied to the side of the printed circuit board on which the components are mounted. DE-A1-3,331,112 describes measures for dissipating the heat from this layer. The layer is a heat conducting sheet metal part, which is affixed to the printed circuit board.
DE-A1-3,035,749 describes a heat dissipating, planar printed circuit board having a core of heat conducting, in particular metallic, material. This core is coated with a copper layer. The copper layer, in turn, carries a layer of anodized electroplated aluminum. The layer of anodized electroplated aluminum is coated with a plastics layer. The layer of anodized electroplated aluminum carries the strip conductors.
In the manufacturing process, the copper layer is electroplated with aluminum. The aluminum layer thus obtained is then converted to anodized aluminum by further treatment.
The heat is dissipated substantially through the metallic core of the printed circuit board. Printed circuit boards having such a metallic core are, however, undesirably heavy. Printed circuit boards of conductive carbon or graphite, which are also suggested in DE-A1-3,035,749, are expensive. The layer of electroplated anodized aluminum is an insulator and does not serve to ensure good heat conduction in the plane of the printed circuit board.
Bores are provided in the printed circuit boards of DE-A1-3,035,749. These bores serve for electrically connecting strip conductors on one side of the printed circuit board with strip conductors on the other side. The function of these bores is not the dissipation of heat from a component to the other side of the printed circuit board.
DE-A1-3,115,017 discloses an electronic component in the form of an integrated circuit which is mounted on a carrier plate, the carrier plate, in turn, being mounted on a printed circuit board. The contact surface with which the carrier plate is mounted on the printed circuit board is metallized for better heat conduction. Metallized bores are provided in the printed circuit board in the region of the component. Through these metallized bores, the carrier plate is is in heat conducting connection with a cooling plate arranged on the back side of the printed circuit board. With this arrangement, one cooling plate is associated with each component. The cooling plates are parts attached to but separate from the printed circuit board.